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PINCOGENESIS—PARTHENOGENESIS IN RABBITS BY GREGORY PINCUS N. T. WERTHESSEN with R. C.JOHNSON* DwightJ. Ingle, previously editor, now advisory editor of thisjournal, wrote the biographical memoir of the late Gregory Pincus for the National Academy of Sciences [I]. A copy of that memoir reached my desk in the spring of 1973 and, since the man of whom he wrote had been my teacher, colleague, adviser, and dearest older friend from 1931 to 1967, I read it with great interest. I found that, of all the commentaries on Pincus I had heard or read, this one gave the most accurate picture of the man that I knew. But I was shocked when I read the section that dealt with Pincus's induction of "artificial" parthenogenesis in rabbit eggs ("Pincogenesis") in the 1930s. Ingle claimed that there was skepticism among some other workers in this field, since no one had repeated the work, and hence considered Pincus's claims to be questionable. In a mixed mood of appreciation for an excellent description of my mentor's career and anger at the fact that colleagues doubted an unequivocal fact of accomplishment on his part, I wrote to Ingle saying in effect that I was there, I helped make it happen. Perhaps the fact that in the preceding period I had learned that two other accomplishments of Pincus's laboratory prior to 1950 had not yet been repeated lent extra vehemence to my language.1 *Department of the Navy, Office of Naval Research, 495 Summer Street, Boston, Massachusetts 02210. Professor R. Christian Johnson, on leave from the University of Wisconsin—Green Bay, is writing a book, Science and Social Reform: The Searchfor a Scientific Contraceptive, in which the story of Pincus and the parthenogenic rabbits will be told in the context of Pincus's other work. We thank Professor Thomas Wegmann and Mr. James Reed of Harvard University for their advice. 'Pincus described in 1937 the culture of a fertilized rabbit egg from its earliest possible removal from the tubes through postimplantation stages. Thirty years later no one else had done this. The objective was to prove that development through the blastocyst stage and further required only a sufficiency of unknown growth requisites present in serum. The culture system devised permitted use of large quantities of flowing rabbit serum while retaining the growing embryo in the circumscribed area [2]. In a national conference [3, p. 393] several speakers had commented on the inability of maintaining organs in vitro for 24 hours let alone observing growth and repair. An appropriate system had been described in 1949 [4]. Pincus had initiated this work in 1935. A portion of human uterus bleeding from a curetted endometrium was observed to regrow endometrium under the influence of estrogen. From that point forward the system was used as a routine research tool. 86 I N. T. Werthessen with R. C. Johnson · Pincogenesis Despite the fact that Ingle and I had had many conversations at Laurentian Hormone Conference meetings since its earliest days, he did not know of my intimate involvement in these studies. He made a point of this in his reply to my letter and his invitation to prepare a rebuttal to the critics. It is important to explain why, although a major portion of my time was spent in this work over a 7-year period, my name appeared only in the "thank you" paragraph at the end of the papers describing parthenogenesis in rabbits. Pincus's research had three facets. One was genetics, the second was gamete behavior, and the third was regulation of the reproductive system . From the third developed his renown as an endocrinologist. This was my area. However, in those days at Crozier's department a student ordinarily did two separate lines of research. One was his professor's research, in which the student acted as a super-technician and received credit for research assistance. This was the price the student paid for support of his own thesis research. If his professor helped in this thesis work (guidance or collaboration at the bench), the professor's name appeared on the papers, usually as senior author. Ifnot, the papers were published under the name...